The field of the invention pertains to fluid tubing couplers and fasteners and, in particular, to fasteners for hydraulic, pneumatic and fuel systems on aircraft wherein unusual and perhaps "exotic" materials are used for weight savings and corrosion resistance. Such fittings are subject to severe vibration and absolutely must not loosen or disassemble during use. As a result military and civilian specifications require assurance that failure will not occur. Conventional construction now requires that the fittings be "wired" and the wires "sealed" to prevent the fasteners from rotating apart during use.
An early patent, U.S. Pat. No. 315,895, discloses a device to retain a packing nut on a valve. The device engages the flats on the nut and is retained by a small screw. U.S. Pat. No. 1,691,851 and more recently U.S. Pat. No. 4,801,160 each disclose a circumferential coil spring having means at one end of the coil spring to engage a ratchet or socket in the member that is to be prevented from rotating.
U.S. Pat. No. 3,343,852 discloses a ball detent device to lock a nut on an electrical connector. The ball detent engages a plurality of grooves in an inside member. U.S. Pat. No. 3,986,731 discloses a tangentially extending external pawl that engages notches in the exterior of the inside member whereas U.S. Pat. No. 3,069,187 discloses an axially extending pawl adapted to engage a plurality of ratchet grooves in the radial face of the other member. Similarly, U.S. Pat. No. 2,489,919, U.S. Pat. No. 2,731,058 and U.S. Pat. No. 4,150,845 all disclose devices that engage ratchet grooves in a radial face on one of the members. U.S. Pat. No. 2,992,018 discloses a circumferential plurality of axial grooves on an inner member and a circumferential plurality of axial grooves on the inside of a nut as axially extended. Splits in the axially extended portion of the nut permit the grooved portion to flexibly expand and ratchet about the inner member.
Most of the devices disclosed above are bulky and complicated with several separate parts or require a complicated geometry be formed on one or both of the members retained to prevent retrograde movement and inadvertent disassembly. Such complications are to be avoided with aircraft couplings and fasteners which are typically formed from expensive, hard, tough and strong metals and alloys. Other common devices rely upon plastic yielding of the threads joining the couplers or fasteners or plastic yielding of a plastic insert. Plastic yielding destroys the reuseability of such capture devices after one or a few disassemblies. With a view toward creating a light, compact and simple capture device that can be retrofitted to existing couplings, applicant has developed the new capture device disclosed below.